Upton was born in St. Joseph, Michigan and raised in Melbourne, Florida. She attended Holy Trinity Episcopal Academy. Her uncle is U.S. Representative Fred Upton. Upton's great-grandfather, Frederick Upton, was co-founder of appliance manufacturer and marketer Whirlpool Corporation. As a young equestrian, Upton showed at the American Paint Horse Association and competed at a national level. With her horse Roanie Pony, she won three APHA Reserve World Championships — 13 and Under Western Riding, 13 and Under Horsemanship, and 14–18 Western Riding. She was named the 13 and Under Reserve All-Around Champion, giving her a total of four reserve championships (2nd place). In addition, Upton ended up third overall on the APHA youth Top Twenty. With a second horse, Zipped, she won 14–18 Western Riding and was included in the top 5 in 14–18 Horsemanship and 14–18 Western Pleasure in 2009.
Upton attended a casting call in Miami for Elite Model Management in 2008 and was signed by them the same day. She eventually moved to New York City, where she then signed with IMG Models.
Upton first modeled for Damien Haumpy Garage, then Dooney & Bourke. She is the 2010–2011 face of Guess. In 2011, Upton appeared in the Sports Illustrated Swimsuit Issue. She was featured in the body paint section and named Rookie of the Year for the issue. She has since modeled for Beach Bunny Swimwear and Victoria's Secret, and has appeared in Complex and Esquire as "The Woman of the Summer". In April 2011 an internet video of her doing the Dougie at a Los Angeles Clippers game went viral and served to increase her popularity. On April 30, 2012, a bikini-clad Upton performing the "Cat Daddy" by The Rej3ctz in a video directed by Terry Richardson also went viral, amassing almost 750,000 views in the first 24 hours. Kate Upton’s "Cat Daddy" moves could land her a cameo in song creator's The Rej3ctz's next video.
Upton made an appearance in a June 2011 episode of Tosh.0, filmed in Fort Cobb, Oklahoma, participating in a segment called "Knife or Banana", emulating a Japanese game show in which she is stabbed with a banana. Upton played in the 2011 Taco Bell All-Star Legends & Celebrity Softball Game at Chase Field in Phoenix, Arizona, in July 2011. Upton's acting debut was in the film, Tower Heist, as Mr. Hightower’s Mistress. She followed up with an appearance in The Three Stooges as Sister Bernice. Upton appeared on the cover of the 2012 Sports Illustrated Swimsuit Issue, unveiled on February 13, 2012, on the Late Show with David Letterman.
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